1. Field of the Invention (Technical Field)
The present invention relates to meat cutting, such as commercial beef cutting, and in particular to an optical probe for automating meat cutting, and specifically to an optical probe for determining the location of the interface between fat material and lean material in a cut of meat.
2. Background Art
Note that the following discussion refers to a number of publications by author(s) and year of publication, and that due to their recent publication dates certain publications are not to be considered as prior art vis-a-vis the present invention. Discussion of such publications herein is given for more complete background and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
In the process of cutting and trimming meats for sale, it is desirable to ascertain the location of the interface between an upper layer of fatty tissue and the underlying lean meat, in order to trim away a desired quantity of fat. These processes can be difficult to perform efficiently, especially in high-volume commercial meat processing facilities. It has been necessary in the past to make an incision into the fat, insert a measuring device therein, and view a scale through the device which indicates fat thickness. The scale is often difficult to read and often the measurement is taken while the carcass is moving down the processing line, leading to a tendency to conduct the measurement in an incomplete manner.
To separate the lean meat from the fatty tissue, it is necessary to determine the interface between the fatty tissue and lean meat tissue (“fat/lean interface”) in the meat carcass. Knowledge of the location of the fat/lean interface aids in the process of trimming a selected amount of fatty tissue from the meat carcass, for example to produce a cut of meat with a selected thickness of fat that is uniformly distributed across the product. Currently, where human workers manually trim the fat from the carcass—which is still generally the norm, even in industrialized nations—they are constantly “poking” the carcass, feeling for the tough membrane that marks the interface, thereby gauging fat thickness. Human tactile estimations of the location of the interface are less than desirable in a variety of ways. Additionally, the location of the fat/lean interface must be known to realize any benefits from an automated trimming operation.
Various mechanisms have been developed to address the need of determining the fat thickness on a meat carcass, and include those described in U.S. Pat. No. 4,078,313 to Hennessy, entitled “Measuring Device,” and U.S. Pat. No. 4,209,878 to Albert, entitled “Automatic Meat Inspecting and Trimming Machine and Method.” The Hennessy patent discusses a device where light is emitted into the meat tissue and reflected light is detected by a center element located within the probe. The size of the Hennessy device and the internal circuitry enclosed within the handle makes it cumbersome to use, and the device tends to mar the meat in the course of taking the measurement. Albert discusses a set of pneumatically operated probes for sensing fat thickness in a meat product, but does not disclose the use of light to detect lean meat or fatty tissue.
Also of note are U.S. Pat. No. 4,246,837 to Chenery, entitled “Meat Cutting Apparatus,” and U.S. Pat. No. 4,825,711 to Jensen et al., entitled “Probe Unit for Automatic Determination of Quality Properties of Meat.” The Chenery patent uses a row of needle probes that are pushed into the meat carcass and sense a change in electrical conductivity between the lean and fat portions in order to determine the fat/lean interface within the meat. Jensen uses a light reflection meter at one end of a meat probe to detect light reflected from the tissue and to determine the type and quality of tissue being penetrated. The light reflector comprises a light diode and photodiode that are secured directly within the probe. Conventional electrical wiring is used to provide energy to the light diode and to receive an amplified signal from the photodiode. U.S. Pat. No. 6,088,114 to Richmond et al., entitled “Apparatus for Use in Determining Meat Tenderness” also provides background information. The use of fiber optics in a fat depth probe is described in an article by H. J. Swatland, entitled “Effect of Connective Tissue on the Shape of Reflectance Spectra Obtained with a Fibre-Optic Fat-Depth Probe in Beef,” Meat Science 57, 2001, pgs. 209-213.
Limitations in these prior art devices include the cumbersome size of the devices and the tendency to leave permanent markings in the meat that is probed, as well as inefficiencies in determining the fat/lean interface. It would be useful if a probe could be designed to be of a very small diameter, on the order of 0.125 inches in diameter, so that the probe can be inserted into the meat sample with minimal damage to the meat. It would also be beneficial to have a device wherein green light can be emitted into the meat sample as fatty tissue and lean meat tissue absorb green light differently. It would also be advantageous for such a device to have the green light source as well as the light detector for return light from the tissue located remotely from the probe so that the probe is less cumbersome and can be lightweight and small in diameter for ease of use and to minimize damage to the meat sample.
Against this background, the present invention was developed.